Abstract 416: Mammographic density and ECM stiffness

Abstract

Abstract Breast tissue homoeostasis depends on the complex regulation of biochemical and biophysical factors present in the extra cellular matrix (ECM). Tumor tissue in mouse and human breast is characteristically stiffer than normal tissue, and changes to the ECM contribute to this phenotype. Breast density is associated with elevated collagen content, while increased deposition of collagen is known to augment ECM stiffness. Mammographic density imaging provides a qualitative description of breast density, and high mammographic density is associated with increased risk to malignancy. However, little is known about the correlation between ECM stiffness and the density in the breast image. Previously, we have used atomic force microscopy (AFM) to characterize the changes in breast tissue stiffness with cancer progression (Levental et al., Cell 2009). We hypothesized that mammographically dense breasts would be stiffer. To further understand the biophysical regulation of breast stiffness, we investigated whether mammographic density is a predictor of ECM stiffness. Towards this goal, we studied tissue samples from prophylactic mastectomies, from women with low versus high mammographic density. Tissue samples were obtained from the peripheral quadrants as well as from the retroareolar (nipple) regions, which are known to be of higher mammographic density. We performed AFM force mapping to characterize the ECM stiffness in the different regions. Our preliminary data indicate a heterogeneous pattern of stiffness within the breast. Moreover, we found that the peripheral terminal ductal lobuli have the most compliant ECM. By contrast, the stroma stiffness in the retroareolar region was 2-fold higher than in the peripheral quadrants. This work demonstrates the technical feasibility of measuring the mechanical properties as well as defined histological characteristics within the same patient specimen. The data suggest that ECM stiffness may be greater in breast tissue of high mammographic density. The correlation between mammographic density and ECM stiffness may reveal the role of collagen status in the risk to malignancy. (supported by W81XWH-05-1-0330 and R01 CA138818-01A1 to VMW, 1U01 ES019458-01 to VMW and ZW, and P50 CA 58207 to JG, VW, SH and LC.) Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 416. doi:10.1158/1538-7445.AM2011-416